Cracking processes



United States Patent O 3,235,484 CRACKING PROCESSES John M. Colt-er,Cleveland, Ohio, assignor to The Lubrizol Corporahon, Wicklilfe, Uhio, acorporation of Ohio No Drawing. Filed Mar. 27, 1962, Ser. No. 182,967 9Claims. (Cl. 20848) The present invention relates, as indicated, toimprovements in processes for the cracking of hydrocarbons such asliquid petroleum hydrocarbons. In a more particular sense, it relates toa method for inhibiting the accumulation of harmful carbonaceousmaterial in refinery cracking units.

Most of the gasoline produced today is obtained by the thermal orcatalytic cracking of heavier petroleum hydrocarbon feed stocks such aslight or heavy gas oils, cycle stocks, virgin or topped crude oils, lubestocks, kerosene, and kerosene-gas oil mixtures. A number of difierentthermal and/or catalytic cracking processes known in the petroleumindustry under designations such as Fluid Process, Thermofor, Houdry,Platforming, Thermal Reforming, Viscosity-Breaking, etc., are employedfor the purpose. Although these various processes diifer considerably asto the precise manner in which the heavier hydrocarbon molecules arecracked to yield gasoline, they all involve the heating of thehydrocarbon feed stock to a high temperature (370-1200 F.) and thepassage of such heated stock, optionally mixed with a cracking catalyst,through heated tubes, reactors, convertors, and tower stills. Regardlessof the particular process used, the cracking operation always results inthe formation of some undesirable carbonaceous material or refinery cokewhich adheres to the tubes, reactors, etc., of the cracking unit andlowers its efiiciency, principally by impeding the flow of the feedstock therethrough and the transfer of heat to or from such stock. Afterenough carbonaceous material has accumulated on the various parts of thecracking unit to lower its efiiciency substantially, the unit must bedismantled, cleaned, and reassembled. Of course, such cleaningoperations are not only tedious and costly, but result in a largeproportion of down-time during which the unit is not functioning.Although the use of modern Platforming and catalytic cracking processeshas reduced the amount of down-time as compared with older, strictlythermal cracking processes, the accumulation of refinery coke stillpresents a problem to the petroleum refining industry.

It is, therefore, an object of the present invention to inhibit theaccumulation of harmful carbonaceous material in refinery crackingunits.

Another object is to disperse the carbonaceous material formed duringthe cracking of a hydrocarbon feed stock throughout said feed stock andthereby inhibit its accumulation on the various parts of refinerycracking units.

Yet another object is to reduce the amount of downtime in the operationof refinery cracking units.

These and other objects of the invention are realized by the provisionof a method for inhibiting the accumulation of carbonaceous material ina refinery cracking unit during the cracking of a hydrocarbon feed stocktherein which comprises dissolving in said feed stock a minorproportion, generally at least about 0.0012 weight percent andpreferably from about 0.0012 to about 0.04 weight percent, of anoil-soluble acylated amine prepared by mixing a substituted succiniccompound selected from the class consisting of substituted succinicacids having the structural formula 3,235,484 Patented Feb. 15, 1966 iceand substituted succinic anhydrides having the structural formula ROHCOo CH2C6 in which structural formulas R is a large, substantiallyaliphatic hydrocarbon radical having at least about 50 carbon atoms,with at least about one-half an equivalent amount of an amine selectedfrom the group consisting of alkylene amines and hydroxyalkylsubstituted alkylene amines, and heating the resulting mixture to efiectacylation and remove the water formed thereby.

It is also desirable, in some instances, to dissolve additionally in thehydrocarbon feed stock a minor proportion of a product prepared byheating one equivalent of an alkylphenol with from about 0.1 to about 10equivalents each of a formaldehyde-yielding reagent and an amine forabout 0.5 to about 10 hours at 250 C. and removing the water which isformed. In addition, benefit is also derived in many cases by theincorpora tion in the hydrocarbon feed stock of known oxidationinhibitors such as hindered phenols (e.g.,2,6-di-tertiarybutyl-4-methyl-phenol and4,4'-methylene-bis-(2,6-di-tertiary-butylphenol), aminophenols,N-alkylated phenylene diamines, phenothiazine, mercapto-benzothiazole,etc.

The oil-soluble acylated amine required for the purposes of thisinvention is described in detail in the copending application of W. M.Le Suer et al., Ser. No. 802,667, filed March 30, 1959, now Patent No.3,172,892. In the interest of not unduly lengthening the presentspecification -it is intended that the disclosure of the said Le Suer etal. application be considered as forming a part of the presentspecification.

In summary, application Ser. No. 802,667 deals with mixing a substitutedsuccinic compound selected from the class consisting of substitutedsuccinic acids having the structural formula and substituted succinicanhydrides having the structural formula in which structural formulas Ris a large, substantially aliphatic hydrocarbon radical having at leastabout 50 carbon atoms, with at least about one-half an equivalent amountof an ethylene amine, and heating the resulting mixture to effectacylation and remove the water formed thereby.

The size of the substituent on the succinic acid or anhydride is ofimportance in the preparation of the acylated amine because it allowsthe preparation of a product which satisfies the objects of thisinvention. It is im portant that this substituent be large, that it haveat least about 50 carbon atoms and preferably at least about 60 carbonatoms in its structure. When this substituent has substantially lessthan 50 carbon atoms, the resulting acylated amine is ineffective forthe purposes of this invention, i.e., it does not have the ability toreduce the accumulation of carbonaceous material in refinery units.

The substituent groups are substantially aliphatic hydrocarbon radicals,including both alkyl and alkenyl radicals. They are commonly derivedfrom polyolefins such as polyethylene, polypropylene, polybutene,polyamylene, etc., containing from about 50 to about 7000 or more carbonatoms, although they may be derived from any large, substantiallyaliphatic hydrocarbon.

The substituted succinic acids and anhydrides which are contemplated asreactants in the process for the preparation of the acylated amine arereadily available from the reaction of maleic anhydride with a highmolecular weight olefin or a chlorinated high molecular weight olefin.The product from such a reaction is the corresponding alkenyl succinicanhydride. The reaction involves merely heating these two reactants at"a temperature of about 150 to 200 C. The reactants in each case areillustrated by the following equations:

In some instances, it is also desirable to make the substituted succiniccompound by introducing chlorine into a heated mixture of maleicanhydride and the polyolefin. It will be appreciated that the reactionmay not go precisely as indicated above, especially with respect to theparticular carbon atom of the olefin or chlorinated olefin reactantwhich ultimately becomes attached to the maleic acid or anhydridereactant, but other than this the equations are believed to beillustrative. Furthermore, although the product of this reaction hasbeen indicated as being an alkenyl succinic anhydride, it is apparentthat similar products can be prepared by this process in which thesubstituent is something other than an alkenyl group. For the purpose ofthe present invention this substituent should, however, be substantiallyaliphatic and in most cases, of course, it will be an alkyl or alkenylgroup. In some cases, however, it may be desirable to employ asubstituted succinic anhydride in which the substituent is derived froma copolymer of styrene and isobutylene, or of a substituted styrene andsome other aliphatic olefin. In these cases the copolymer will besubstantially aliphatic, that is, the composition of the copolymer willbe such that the non-aliphatic portion does not substantially exceedabout 30 percent of the Whole. Thus, a copolymer of 90 percent ofisobutene and percent of styrene or of 80 percent of propylene andpercent of alpha-methylstyrene is useful to provide the large,substantially aliphatic substituent.

The most commonly used sources of the substantially aliphatichydrocarbon substituents are the polyolefins. These are illustrated bypolyethylene, polypropylene, polyisobutene, polyisoamylene,polyisohexylene, etc. A particularly preferred polyolefin for this useis polyisobutene. Thus the condensation of a polyisobutene containing atleast about 50 carbon atoms, preferably at least about 60 carbon atoms,and most desirably from about 100 to about 130 carbon atoms, with maleicanhydride yields an alkenyl succinic anhydride which upon furtherreaction with an ethylene amine produces a material which isparticularly effective as the acylated amine required for the purposesof the present invention.

The substituted succinic anhydride ordinarily is reacted directly withthe ethylene amine, although in some instances it may be desirable firstto convert the anhydride to the acid before reaction with the ethyleneamine. In other circumstances it may be desirable to prepare thesubstituted succinic acid by some other means and to use an acidprepared by such other means in the process. In any event, either theacid or the anhydride may be used in the preparation of the acylatedamine.

The term ethylene amine is used in a generic sense to denote a class ofpolyamines conforming for the most part to the structure in which x isan integer and R is a low molecular weight alkyl radical or hydrogen.Thus it includes, for example, ethylene diamine, diethylene triamine,triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine,etc. These compounds are discussed in some detail under the headingEthylene Amines in Encyclopedia of Chemical Technology, Kirk and Othmer,volume 5, pages 898- 905, Interscience Publishers, New York (1950). Suchcompounds are prepared most conveniently by the reaction of ethylenedichloride with ammonia. This process results in the production ofsomewhat complex mixtures of ethylene amines, including cycliccondensation products such as piperazines, and these mixtures find usein the preparation of the acylated amine. On the other hand, quitesatisfactory products may be obtained also by the use of pure ethyleneamines. An especially useful ethylene amine for reasons of economy aswell as effectiveness is a mixture of ethylene amines prepared by thereaction of ethylene chloride and ammonia, having a composition whichcorresponds to that of tetraethylene pentamine. This is available in thetrade under the trade name Polyamine H. Another group of very usefulethylene amine, with a preference expressed for a mixture of abouttetramine with 01-10 parts by weight of diethylene triamine, with apreference expressed for a mixture of about 3 parts of triethylenetetramine with about 1 part of diethylene triamine.

It has been noted that at least about one-half an equivalent of theethylene amine per equivalent of the substituted succinic compoundshould be used to produce a product which is satisfactory for thepurposes of the present invention. Amounts of the ethylene amine rangingfrom about 0.5 to about 8 equivalents, preferably from about 1 to about4 equivalents, per equivalent of substituted succinic compound aregenerally used. Amounts greater than 8 equivalents of ethylene amine perequivalent of substituted succinic compound may also be used if desired,but there appears to be no advantage in the use of such large amounts ofthe ethylene amine reactant. The chemical equivalency of the ethyleneamine reactant is based upon the nitrogen content, i.e., one having 4nitrogens per molecule has 4 equivalents per mole.

In the preparation of the acylatedamine, the ethylene amine and thesubstituted succinic compound are mixed and heated at a temperaturewithin the. range from about C. to about 200 C., preferably C. to C.,until most or all of the water of reaction has been removed. Thus, auseful method of carrying out this step is to add some toluene or xyleneto the reaction mixture and remove the water of reaction by azeotropicdistillation.

It has also been found that in lieu of the ethylene amine reactant, onecan use for the purpose of the present invention any alkylene amine orhydroxyalkyl substituted alkyleue amine reactant conforming for the mostpart to the structure in which n is an integer, A is hydrogen, ahydrocarbon radical, or a hydroxyalkyl radical, and Q is a divalentaliphatic radical containing at least 2 carbon atoms. The A substituentsin the above formula can also be considered as forming a divalentalkylene radical, in which instance a cyclic structure results. Q isgenerally an alkylene radical such as ethylene, trimethylene,tetramethylene, etc., although in certain instances it may be analiphatic radical which contains ether or sulfide substituents such as,e.g., an alkylene-O-alkylene or alkylene-S-alkyleneradical.

Specific examples of such amine reactants are trimethylene diamine,di-(trimethylene)triamine, tris (trimethylene)tetramine,tri-(hexamethylene)tetramine, decamethylene diamine, N-octyltrimethylene diamine, N,N-dioctyl trimethylene diamine, N-(2hydroxyethyl)ethylene (ll;

5 amine, piperaz ine, 1-(2-aminopropyl)piperazine, 1,4-bis-(Z-aminoethyl)piperazine, 1-(2 hydroxethyl)piperazine,di-(hydroxypropyl)substituted tetraethylene pentamine,N-3-(hydroxypropyl)tetramethylene diamine, pyrimidine,Z-methyl-imidazoline, polymerized ethylene imine, and 1,3-bis-(Z-aminoethyl)imidazoline.

Specific examples of acylated amines which are disclosed in detail inapplication Ser. No. 802,667 and which are useful as the acylated amineherein are shown in Table I.

seemed.

6 grams (1.89 equivalents) of a polyisobutene-s11bstituted succinicanhydride similar to that described in Example 1 but having anequivalent Weight of 530, using 300 grams of xylene as a reactionsolvent. Upon removal of the xylene solvent, the acylated amine remainsas the residue. It contains 4 percent nitrogen.

Example 4 In a manner like that described in Example 1, 418 grams (3.78equivalents based on nitrogen) of bis-(3- TABLE I Acylated AminePrepared From Example No. of Serial No. I

802,667 Succinic compound Equiv- Amine Equivalents alents 1Polyisobutenesubstituted 1. Diethylene triamiue 1.0

succinic anhydride. 2. do 1. 0 Ethylene diamine 1.0 3. rln 1.0 Anethylene amine mixture 1.

corresponding to triethylene tetramine. do 1.0 Triethylene tetramine 1.5 do 0.78 Polyamine 1. 55 do 1.0 Ethylene diamme 1. 5Polyisobutenesubstituted 1.0 Polyamine H 1.0

succinic anhydride. Polypropylene substituted 0.52 do 0.52

succinic anhydride. Isobutene-styrene copolymer 4 0.51 Polyarmne H 0.51

substituted succinic anhydride. Polyisobutene substituted 2. 55 do 2. 55

succinic anhydride.

1 Polymer contains an average of about 60 carbon atoms. 2 Polymercontains an average of about 71 carbon atoms. 3 Polymer contains anaverage of about 62 carbon atoms.

4 Copoly'mer contains an average of about 86 carbon atoms and a weightratio of isobutene units: styrene units of 94.6.

5 Polymer contains an average of about 3,600 carbon atoms.

Additional examples of acylated amines useful for the purposes of thisinvention are as follows. Unless specified otherwise, all parts andpercentages are by weight.

Example 1 A polyisobutene-substituted succinic anhydride is prepared bythe reaction of a chlorinated polyisobutene (ca. 4 percent chlorinecontent) with maleic anhydride at 200 C. for a period of about 4 hours.The polyisobutene has an average molecular weight of 850 (i.e., containsan average of about 60 carbon atoms per mole) and the resulting alkenylsuccinic anhydride is found to have an equivalent Weight of 515. Amixture of 3 parts of triethylene tetramine and 1 part of diethylenetriamine, by weight, in the amount of 279 grams (7.76 equivalents basedon nitrogen) is added to a solution of 1000 grams (1.94 equivalents) ofthe alkenyl succinic anhydride in 200 grams of toluene over a period of4 minutes at 5788 C. After the initial exothermic reaction subsides, thewhole is heated for 5 hours at 155 C. The water of reaction is collectedin a sidearm water trap and amounts to about 26 grams. The reaction massis then stripped of solvent by heating at 160 C./5 mm. Hg untildistillation ceases. The residue is an acylated amine having a nitrogencontent of 7.54 percent.

Example 2 In a manner like that described in Example 1, 249 grams (4equivalents based on nitrogen) of bis-(3-aminopropyl)amine is mixed witha solution in 266 grams of toluene of 920 grams (1.33 equivalents) of apolyisobutene-suhstituted succinic anhydride similar to that describedin Example 1 but having an equivalent weight of 690. The whole is heatedfor 6 hours under reflux and then heated to 220 C./ 3 mm. Hg to removethe solvent. The residue is an acylated amine having a nitrogen contentof 4.0 percent.

Example 3 In a manner like that described in Example 1, 333 grams (3.78equivalents based on nitrogen) of bis-(3- aminopropyl)ether of ethyleneglycol is reacted with 1000 aminopropyl)ether of diethylene glycol isreacted with 1000 grams (1.89 equivalents) of apolyisobutene-substituted succinic anhydride similar to that describedin Example 1 but having an equivalent weighs of 530, using 300 grams oftoluene as a reaction solvent. Upon removal of the toluene solvent, theacylated amine remains as the residue. It contains 3.8 percent nitrogen.

Example 5 In a manner like that described in Example 1, 194 grams (3.74equivalents based on nitrogen) of N-(2- a'minoethyl) ethanolamine isreacted with=1000 grams (1.87 equivalents) of apolyisobutene-substituted succinic anhydride similar to that describedin Example 1 but having an equivalent Weight of 535, using 786 grams oftoluene as a reaction solvent. Upon removal of the toluene solvent, theacylated amine remains as the residue. It contains 4.3 percent nitrogen.

Example 6 1000 parts of a polyisobutene having a molecular weight ofabout 1500 (contains an average of about 107 carbon atoms per mole) and123 parts of maleic anhydride are introduced into a reaction vessel andheated to 175 C. 270 parts of chlorine gas is introduced slowly into theheated reaction mass at a temperature of 175 200 C. over a period ofabout 16 hours. The resulting polyisobutene-substituted succinicanhydride shows a saponification number of 116.

524.3 parts (1.074 equivalents) of the above-describedpolyisobutene-substituted succinic anhydride, 51.3 parts (1.429equivalents based upon nitrogen) of a mixture of 3 parts by weight oftriethyiene tetramine with 1 part by weight of diethylene triamine, and241.8 parts of xylene solvent are heated for 10.75 hours at 155 C. whilewater is removed by means of a side-arm water trap. The product, a 70percent solution of the desired acylated amine in xylene solvent,contains 222 percent nitrogen.

7 Example 7 2170 parts of a polyisobutene having an average molecularweight of about 900 (equivalent to about 65 carbon atoms per mole) isintroduced into a reaction vessel and heated to 104 C. 226.8 parts ofchlorine gas is introduced over an 8.5 hour periodwhile the reactiontemperature is maintained between 105 and 110 C. Thereafter, the wholeis blown with nitrogen gas for 0.5 hour to remove any occluded HC].There is obtained 2280 parts of a chlorinated polyisobutene containing4.4 percent chlorine. This chlorinated polyisobutene is mixed with 250parts of maleic anhydride and the whole is heated from 105 C. to 200 C.over a 10-hour period. The product in the reaction vessel is apolyisobutene-substituted succinic anhydride having a saponificationnumber of 101 and an equivalent weight of 555.

1110 parts (2.0 equivalents) of the above-describedpolyisobutene-substituted succinic anhydride, 800 parts of SAE 10mineral oil, and 108 parts (2.0 equivalents) of a commercial,polymerized ethylene imine having a molecular weight of about 1200 andcontaining 25.9 percent nitrogen (available under the trade designationPolyamine 1200") are added to a reaction vessel in the stated order. Anexothermic reaction causes the temperature to rise 20 C. The whole isthen heated for hours at 150l55 C. while nitrogen is blown therethroughto remove the water of reaction. The product, a 60 percent solution ofthe desired acylated amine in SAE mineral oil, is found to contain 1.42percent nitrogen.

As indicated previously, it is also desirable in some instances todissolve additionally in the hydrocarbon feed stock a minor proportion,generally from about 0.0003 to about 0.02 weight percent, of a productprepared by heating 1 equivalent of an alkylphenol with from about 0.1to about 10 equivalents of a formaldehyde-yielding reagent and an aminefor about 0.5 to about 10 hours at 80- 250 C. and removing the waterwhich is formed. If desired, a solvent such as toluene or xylene may beadded to the reaction mixture to assist in the removal of water. Theincorporation of such a product in a hydrocarbon feed stock appears toinhibit to a certain extent the formation of carbonaceous material. andthus aids the acylated amine in its role of inhibiting the accumulationof said carbonaceous material in refinery cracking units.

The alkylphenol reagent may be either a mono-alkyl or a poly-alkylphenol. The alkyl groups may be of any size, ranging from methyl up toalkyl groups derived from polyolefins having molecular weights as highas 50,000 or more. Preferably the alkylphenol is a mono-alkyl phenol inwhich the alkyl group contains from 1 to about 30 carbon atoms,preferably at least about 4 carbon atoms. Typical examples of usefulalkyl phenols include, e.g., ortho, meta, and para-cresols; ortho, andpara-ethylphenols; ortho, para-diethylphenol, para-isopropylphenol,paratertiary butylphenol, ortho n-amylphenol, para-tertiary amylphenol,heptylphenol, diisobutylphenol, n-decylphenol, wax-alkylatedalpha-naphthol, Wax-alkylated phenol, and polyisobutene-substitutedphenol in which the polyisobutene substituent contains from about 12 toabout 76 carbon atoms. The alkylphenol may also contain substituentgroups such as, e.g., chloro, fluoro, nitro, alkoxy, sulfide, nitroso,etc. A particular preference is expressed for heptylphenol. Also usefulare polyhydric phenols such as alkylated resorcinols, alkylatedcatechols, alkylated pyrogallols, and their substitution products. Forthe purposes of the present specification and claims, one equivalent ofan alkylphenol is the same as one mole thereof.

The formaldehyde-yielding reagent may be any one of the variousformaldehydes or formaldehyde derivatives such as formaldehyde gas,formalin, alpha-trioxymethylene, paraformaldehyde, formaldehydedipropylacetal, formaldehyde dimethylacetal, and the like. Oneequivalent, as applied to the formaldehyde-yielding reagent, is thatamount which supplies one mole of HCHO.

The amine reagent may be any one of the various substituted orunsubstituted amines such as the alkylene amines and thehydroxyalkyl-substituted alkylene amines described earlier in connectionwith the preparation of the acylated amine, as well as any of thevarious aliphatic, cycloaliphatic, or heterocyclic amines such asaminoethyl piperazine, 2,2,4,6,6-pentamethyl tetrahydropyrimidine,ethylamine, diethylamine, diallylamine, ethanolamine, diethanolamine,2-methyl-2-aminopropanol-l, cyclohexylamine, dicyclohexylamine,methylcyclohexylamine, octylamine, dioctylamine, stearylamine, andtertiary-alkyl primary amines such as tertiary-dodecyl primary amine,tertiary-tetradecyl primary amine, etc., a number of which primaryamines are available commercially under the trade designation Primenes.In some instances, it is also possible to use aromatic amines eitheralone or in admixture with any of the above-described-non-benzenoidamines. Examples of useful aromatic amines include aniline, N-methylaniline, alpha-naphthylamine, betanaphthylamine, etc. It is preferred,however, to use an alkylene amine, with a further preference expressedfor an ethylene amine. With respect to the amine reagent employed, itappears to be necessary only that it contain at least one amino hydrogenatom (i.e., a hydrogen atom bonded to an amino nitrogen atom). As setforth earlier, for the purposes of the present specification and claimsone equivalent of an amine is that amount of an amine which contains onenitrogen atom, thus, one mole of an amine such as ethylene diaminecontains 2 equivalents thereof.

The following specific examples illustrate in detail the preparation ofalkylphenol-formaldehyde-amine reaction products which are useful asauxiliary addition agents for the purposes of the present invention.Unless specified otherwise, all parts and percentages are by weight.

Example 8 2500 grams (13.02 equivalents) of heptylphenol, 500 grams ofxylene solvent, 215 grams (5.21 equivalents) of a commercial mixture ofethylene amines having a composition corresponding to that oftetraethylene pentamine, 165 grams (5.21 equivalents) of commercial,percent paraformaldehyde are added in the stated order to a reactionvessel. An exothermic reaction causes the temperature of the reactionmass to rise to about 50 C. The whole is then heated from C. to 160 C.over a period of 2.5 hours while the xylene-water azeotrope is removed.grams of Water is separated from the xylene-water azeotrope and thexylene is added to the cooled contents of the reaction vessel. 689 gramsof additional xylene is added and the whole is filtered. The filtrate, a70 percent solution of the desired product in xylene, is found tocontain 1.84 percent nitrogen.

Example 9 1098 grams (5.71 equivalents) of heptylphenol, 541 grams ofxylene solvent, 108 grams (2.855 equivalents) of tetraethylenepentamine, and 90.3 grams (2.855 equivalents) of commercial, 95 percentparaformaldehyde are added in the stated order to a reaction vessel. Anexothermic reaction reaction causes the temperature to rise to about 40C. The whole is then heated from 105 C. to 162 C. over a period of 1.75hours while water is removed as a xylene-water azeotrope. The water (61grams) is removed from the xylene-water azeotrope and the xylene isreturned to the cooled reaction vessel. Filtration of the reactionvessel contents yields the product, a 70 percent solution of the desiredalkylphenol-formaldehyde-amine reaction product in xylene solvent. Theproduct is found to contain 2.0 percent nitrogen.

Example 10 688 grams (3.34 equivalents) of diisobutylphenol, 327 gramsof xylene solvent, 54.5 grams (1.339 equivalents) of a commercialmixture of ethylene amines having a composition corresponding to that oftetraethylene pentamine, and 42 grams (1.338 equivalents) of commercial,95 percent paraformaldehyde are added to a reaction vessel in the statedorder. An exothermic reaction carries the temperature to 60 C. The wholeis then heated from 100 C. to 168 C. over a two-hour period while thewater of reaction is removed by means of a xylenewater azeotrope. Thewater (29 grams) is separated and the xylene is returned to the cooledreaction vessel. The product, a 70 percent solution of thealkylphenol-formaldehyde-amine reaction product in xylene, is found tocontain 1.76 percent nitrogen.

Example 11 1982 grams (4.27 equivalents) of polyisobutene-substitutedphenol in which the polyisobutene substitutent contains an average ofabout 20 carbon atoms, 200 grams of toluene, 806 grams (21.35equivalents) of tetraethylene pentamine, and 134 grams (4.27equivalents) of commercial, 95 percent paraformaldehyde are added to areaction vessel in the stated order. An exothermic reaction causes thetemperature to rise to 39 C. The whole is heated from 113 C. to 205 C.over a period of 4 hours and the toluene-water azeotrope is collected.90 grams of water is separated from the toluene-water azeotrope. Theresidue in the flask is stripped to 238 C./ 2 mm. Hg and then dilutedwith 405 grams of SAE mineral oil. The product, an 85 percent solutionof the alkylphenolformaldehyde-amine reaction product in mineral oil, isfound to contain 6.01 percent nitrogen.

Example 12 262 grams (1 equivalent) of dodecyl phenol, 121 grams ofxylene solvent, 16.5 grams (0.4 equivalent) of a commercial mixture ofethylene amines having a composition corresponding to that oftetraethylene pentamine, and 13 grams (0.4 equivalent) of commercial, 95percent paraforrnaldehyde are added in the stated order to a reactionvessel. An exothermic reaction causes the temperature to rise from 25 C.to about 30 C. The whole is heated from 115 C. to 185 C. while water isremoved by means of the xylene-water azeotrope. The water (8.5 grams) isseparated from the xylene and the xylene is returned to the cooledreaction vessel. The product, a 70 percent solution of the desiredalkylphenol-formaldehyde-amine reaction product in xylene, is found tocontain 1.39 percent nitrogen.

Example 13 672 grams (3.5 equivalents) of heptylphenol, 497 grams ofxylene solvent, 452 grams (10.5 equivalents) of aminoethyl-piperazine,and 110.5 grams (3.5 equivalents) of commercial, 95 percentparaformaldehyde are added in the stated order to a reaction vessel. Anexothermic reaction causes the temperature to rise from 23 C. to 72 C.The whole is heated from 94 C. to 150 C. over a period of 4.5 hourswhile water is removed by means of the xylene-water azeotrope. Water (77grams) is separated from the xylene-water azeotrope and the xylene isreturned to the cooled reaction vessel. The product, a 70 percentsolution of the desired alkylphenol-formaldehydeamine reaction productin xylene, is found to contain 8.6 percent nitrogen.

Example 14 1156 grams (6.02 equivalents) of heptylphenol, 1017 grams ofxylene solvent, 1150 grams (6.02 equivalents) of a commercial mixture ofC -C tertiary-alkyl primary-amines, and 190 grams (6.02 equivalents) ofcommercial, 95 percent paraformaldehyde are added in the stated order toa reaction vessel. An exothermic reaction 10 causes the temperature torise to 38 C. The whole is then heated from 96 C. to 175 C. over aperiod of 3.75 hours while water is removed by means of the xylenewaterazeotrope. The water (124 grams) is separated from the xylene-waterazeotrope and the xylene is returned to the cooled reaction vessel. Theproduct, a 70 percent solution of the desiredalkylphenol-formaldehyde-amine reaction product in xylene solvent, isfound to contain 2.44 percent nitrogen.

Example 15 478 grams (2.49 equivalents) of heptylphenol, 319 grams ofxylene solvent, 242 grams (2.49 equivalents) of diallylamine, and 79grams (2.49 equivalents) of com mercial, percent paraformaldehyde areadded in the stated order to a reaction vessel. An exothermic reactioncarries the temperature from 22 C. to 63 C. The whole is then heatedfrom 98 C. to 164 C. over a period of 4.75 hours while water is removedby means of the xylene-water azeotrope. The water (54 grams) isseparated from the xylene-water azeotrope and the xylene is returned tothe cooled reaction vessel. Filtration of the xylene solution yields theproduct, a 70 percent solution of the desiredalkylphenol-formaldehydeamine reaction product in xylene. It is found tocontain 3.08 percent nitrogen.

Example 16 995 grams (5.18 equivalents) of heptylphenol, 512 grams ofxylene solvent, 184.5 grams (2.056 equivalents) of2-amino-2-methyl-l-propanol, and 65.5 grams (2.056 equivalents) ofcommercial, 95 percent paraformaldehyde are added in the stated order toa reaction vessel. An exothermic reaction carries the temperature from35 C. to about 45 C. The whole is then heated from C. to 159 C. over aperiod of 1.25 hours while water is removed by means of the xylene-waterazeotrope. The water (46 grams) is separated from the xylene-waterazeotrope and the xylene is returned to the cooled reaction vessel. Theproduct, a 70 percent solution of the desiredalkylphenol-formaldehyde-arnine reaction product in xylene, is found tocontain 1.56 percent nitrogen.

The value of the herein described method of preventing the accumulationof carbonaceous material in refinery cracking units was investigated bymeans of a laboratory test apparatus known as a CRC (Committee on FuelResearch) Fuel Coker, Model 01FC-61, manufactured by the ErdcoEngineering Corporation of Addison, Illinois. A description of the testapparatus and test procedure follows.

The hydrocarbon feed stock to be tested is stored in a five-gallonreservoir from which it is pumped through a rotameter to the testapparatus. The pump, which maintains psi. gauge pressure on the system,is protected by means of an over-pressure switch, an underpressureswitch, and a line filter. The test apparatus has two heated units, thepreheater and the filter body. The preheater consists of an aluminumouter tube and a 'li -inch outside diameter by l8-inch aluminum innertube in which a heating element is inserted in a manner such that thefeed stock is heated as it flows between the outer and the inner tube.The heated filter section contains a sintered stainless steel filterdisk which traps carbonaceous material. A 30-inch mercury manometer isused to measure the pressure drop across the filter. A threevalveby-pass system is installed so that the feed stock may by-pass thefilter if the pressure drop exceeds about 26 inches of mercury. The feedstock flows from the filter through a water cooler and a flow controlneedle valve, which is protected by a line filter, to the spent feedstock reservoir. In preparation for the test, the preheater and filterunits are disassembled and thoroughly cleaned with solvent, scouringpowder, and once more with solvent. After having dried, the units arereassembled and the preheater tube, which has been polished to a mirrorfinish using a good grade of metal polish, is installed. The entiresystem is then cleaned again by pumping about one gallon of solvent (forexample, a mixture of equal volumes of benzene, acetone, andisopropanol) through the apparatus. During this cleaning period thefilter does not contain the sintered disk. After the solvent has beendrained from the apparatus, a new sintered filter disk is inserted andthe unit is ready for the test.

Five gallons of filtered hydrocarbon feed stock is charged to thereservoir and air is blown through the feed stock by means of a frittedglass dispersion tube for 3 minutes. The feed stock is then pumpedthrough the apparatus for 10 minutes, during which time the flowrate isadjusted to 610.1 pounds per hour by means of a flow control valve andthe rotameter. The test is then started by turning on the heaters androuting the discharge feed stock to the feed stock reservoir. The testtemperatures (preheater at 400:5" F. and filter at 500i10 F.) should beobtained in approximately 10 minutes, at which time the manometer isadjusted for the initial reading. The time when the test temperaturesare reached is noted as apparatus prepared for test. The test periodconsists of 300 minutes during which the temperatures of the apparatusare maintained by adjusting the wattmeters which form an integral partof the test apparatus. The flow rate is controlled by means of therotameter and is checked by hourly weighings. The pressure drop acrossthe filter is also recorded at periodic intervals. If the pressure dropexceeds 26 inches of mercury, the by-pass valve is opened and the testis con tinued for the prescribed total of 300 minutes. At the end of thetest, the heaters are turned off and the unit is cooled to 150 F. withthe test feed stock in it, and then the unit is drained and disassembledfor inspection. The pressure drop across the filter and the deposits onthe preheater tube are recorded.

The results in Table II show the beneficial effects of an acylated amineof the present invention and of' a mixture thereof with analkylphenol-formaldehyde-amine reaction product in inhibiting theaccumulation of carbonaceous material on the preheater tube and thefilter of the test apparatus, as shown by the deposits on the preheatertube and the pressure drop across the filter, respectively. A largepressure drop indicates the accumulation of a considerable amount ofcarbonaceous material on the filter. Conversely, a small pressure dropindicates that little cabonaceous material has deposited'on the filter.It will be noted that the alkylphenolformaldehyde-amine product alonewas not'very effective, but that it was beneficial when used incombination with an acylated amine.

TABLE II.CFR FUEL COKER TEST Pressure Hydrocarbon feed stock; 1:1 byDeposits on predrop across weight mixture of gas oil and heater tube thefilter in kerosene plusinches of mercury A. (Control) Very heavy 1 25. 2B. 0.00667 of the alkylphenol- Moderately heavy... 20. 5

tormaldehydeamine reaction product of Example 8 (contains 30% of xylenesolvent). I 0. 0.0066% of the acylated amine Very light 0.15

of Example 6 (contains 30% of the xylene solvent). D. 0.0066% of a 3:1weight mix- -.-..do 0.

ture of the products of Examples 6 and 8, respectively (contains 30% ofxylene solvent)- E. 0.0077% of the acylated amine Light 0. 1

of Example 7 (contains 40% SAE 10 mineral oil).

1 This pressure drop occurred after 103 minutes and the by-pass valveopened at this time.

A field test of additive combination D of Table II in a catalyticcracking refinery unit operating on a gas oil feed stock (additivepresent in the amount of 30 pounds per thousand barrels of gas oil feedstock or approximately 0.01 weight percent) indicates that the periodbetween downtime for cleaning can be extended substantially by the useof this additive combination.

What is claimed is:

1. A method for inhibiting the accumulation of carbonaceous material ina refinery cracking unit during the cracking of a hydrocarbon feed stocktherein which comprises dissolvingin said feed stock a minor proportionof an oil-soluble acylated amine prepared by mixing a substitutedsuccinic compound selected from the class consisting of substitutedsuccinic acids having the structural formula and substituted succinicanhydrides having the structural formula or-rroo in which structuralformulas R is a large hydrocarbon radical having at least about 50carbon atoms, said radical being at least about percent aliphatic, withat least about one-half an equivalent amount of an amine selected fromthe group consisting of alkylene amines and hydroxyalkyl substitutedalkylene amines, and heating the resulting mixture to effect acylationand remove the water formed thereby.

2. A method in accordance with claim 1 further characterized in that atleast about 0.0012 weight percent of said acylated amine is dis-solvedin said hydrocarbon feed stock.

3. A method in accordance. with claim 1 further characterized in that Rof the substituted succinic compound contains at least about 60 carbonatoms.

4. A method in accordance with claim 1 further characterized in that Rof the substituted succinic compound is a radical derived from asubstantially aliphatic polyolefin.

5. A method in accordance with claim 1 further characterized in that theamine is an alkylene amine.

6. A method for inhibiting the accumulation of carbonaceous material ina refinery cracking unit during the cracking of a hydrocarbon feed stocktherein which comprises dissolving in said feed stock from about 0.0012to about 0.04 weight percent of an oil-soluble acylated amine preparedby mixing a substituted succinic compound selected from the classconsisting of substituted succinic acids having'the structural formulaR-CH-COOH Hr-COOH and substituted succinic anhydrides having thestructural formula 13 minor proportion of a product prepared by heatingone equivalent of an alkylphenol with from about 0.1 to about 10equivalents each of a formaldehyde-yielding reagent and an amine forabout 0.5 to about 10 hours at 80- 250 C. and removing the water whichis formed.

9. A method in accordance With claim 8 characterized further in that thealkylphenol is heptylphenol, the formaldehyde-yielding reagent isparaformaldehyde, and the amine is a mixture of ethylene amines having acomposition corresponding to that of tetraethylene pentamine.

1 4 References Cited by the Examiner UNITED STATES PATENTS DELBERT E.GANTZ, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner.

1. A METHOD FOR INHIBITING THE ACCUMULATION OF CARBONACEOUS MATERIAL INA REFINERY CRACKING UNIT DURING THE CRACKING OF A HYDROCARBON FEED STOCKTHEREIN WHICH COMPRISES DISSOLVING IN SAID FEED STOCK A MINOR PROPORTIONOF AN OIL-SOLUBLE ACYLATED AMINE PREPARED BY MIXING A SUBSTITUTEDSUCCINIC COMPOUND SELECTED FROM THE CLASS CONSISTING OF SUBSTITUTEDSUCCINIC ACIDS HAVING THE STRUCTURAL FORMULA